Re: Why am I getting small sparks? Am I underpowered? (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

---------- Forwarded message ----------
Date: Thu, 09 Aug 2007 18:25:45 -0700
From: Barton B. Anderson <bartb@xxxxxxxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: Why am I getting small sparks? Am I underpowered? (fwd)

Hi Treavor,

I don't know if you have tried measuring your caps, but always a good 
idea with bottle caps. I suspect a little under 1nF per bottle. The 
15/30 NST in a static gap application would enjoy a cap value of about 
8nF. Before doing too much, I recommend adjusting what you have now to a 
balance of components. To do this, I recommend removing 4 bottles and 
using only 10 for about 9.5nF. This will dramatically improve the bps to 
a normal level (it's likely way down there right now). The coil will 
resonate at about 230kHz, so about turn 11 with 10 bottles. For some 
practical numbers, if your using 1/4" bolts in the gap, set the gap 
distance to 0.375" or less. If 1/2" bolts, 1/4" or less. Note, the bolt 
gaps will get hot quickly. Hard to cool down also. So maybe short runs 
with time between runs to allow cool down. Multisegments are better for 
cooling and longer runs without heat. Bottle caps are notorious for 
corona and there are losses associated with that. The greatest losses 
are usually in the gap however. When you get the chance, I recommend 
replacing the bottles with an MMC (stable, high energy, low loss, and 
easy to build).

Take care,
Bart



Tesla list wrote:

>---------- Forwarded message ----------
>Date: Fri, 10 Aug 2007 18:38:35 +0000
>From: Trevor Keast <trevor_keast@xxxxxxxxxxx>
>To: tesla@xxxxxxxxxx
>Subject: Why am I getting small sparks? Am I underpowered?
>
>Hi Guys,
> 
>I managed to reach 'first light' with my coil last night however I was unable to get the spark length that I was hoping for and feel I may be underpowered.
> 
>A basic overview of my coil is as follows:
> 
>6 inch secondary diameter
>24 inch secondary length
>approx 900 windings on secondary (24 AWG magnet wire)
>13 Turns on primary made from 1/4 copper tube
>static spark gap
>beer bottle cap (14 bottles)
>15,000V 30mA NST
>4 inch dryer tube toroid (approx 12in diameter)
> 
>I tuned it as best I could but was unable to get sparks bigger than about 6 inches.  They were also quite dim and could hardly be seen unless in the dark.
> 
>I am wondering if I am underpowered?  How can I improve spark length?
> 
>I greatly appreciate any advice or comments.
> 
>Regards,
> 
>Trevor.
>_________________________________________________________________
>Feel like a local wherever you go with BackOfMyHand.com
>http://www.backofmyhand.com
>
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